This invention relates to keypads and, more particularly, to a button which is removable from and insertable into the keypad from the exterior of a housing containing the keypad.
Telephones have keypads which include dial buttons and feature buttons, where the buttons are typically labeled with the dial number or feature identification. When a telephone is used in different countries, the features may have different identifications corresponding to the different languages. In addition, field upgrades as a result of new software may change the features available on the telephone set. It would therefore be desirable to be able to change the keypad buttons to accommodate different labeling.
A common telephone keypad construction includes a printed circuit board having spaced switch terminals thereon. A rubber dome membrane is positioned over the circuit board with carbon pills in aligned registry over pairs of the switch terminals so that depression of a rubber dome and its associated carbon pill results in the bridging of the associated spaced switch terminals (i.e., closure of the associated switch). The rubber dome is formed with an upwardly extending tower above the carbon pill and a keypad button lightly frictionally engages this tower. The keypad housing is formed with an array of openings in positions corresponding to the positions of the switches and is placed over the membrane with the buttons extending through respective ones of the openings. The buttons and the housing have interfering structure so that the buttons cannot be removed upwardly from the housing. Therefore, in order to change a button, the telephone must be disassembled, the button replaced, and the telephone then reassembled. Accordingly, it would be desirable to provide a button construction wherein the button is removable and insertable without requiring the disassembly and subsequent assembly of the telephone while at the same time providing resistance to inadvertent removal of the button.